The invention relates to a position adjustment system having particular applicability to surgical instrumentation.
In the event of traumas, simple or multiple fractures of one or more vertebrae in the spine can give rise to various configurations that require corrective movements to be applied in order to return the spine to its original shape, in particular concerning the curvature involved in lordosis and kyphosis. Special instruments are used for this purpose that make such restoration possible in co-operation with osteosynthesis systems that are known from elsewhere. Document DE G-91-12 466.2 describes such instrumentation including an adjustment system which comprises a threaded rod having two oppositely-handed threads situated on either side of drive means. Each of the threads engages in a tapped bore of a body connected to an element of the instrumentation. Operating such a system is lengthy because of the pitch of the threads and also because of the fact that during handling, surgical gloves come into contact with the threads which have sharp edges that are liable to catch and tear said gloves, thus requiring additional precautions to be taken. This lengthens the time required to perform an operation which increases the likelihood of harm to the patient.
An object of the invention is to provide an adjustment system for instrumentation for surgery of the spine, which can be put into place precisely and quickly.
To do this, according to the invention, there is provided a position-adjustment system, with particular applicability for. surgical instrumentation, in particular for surgery of the spine. The system comprises an elongate member, which, as known to those of ordinary skill in the art of surgical instrumentation, is suitable for being connected to a first element of the instrument. The system further comprises a body suitable for being fastened to the elongate member and for being connected to a second element of the instrument, as well as connection means for connecting the elongate member to the body. The system is arranged to have an unlocked state in which the connection means allow the elongate member to slide relative to the body and a locked state in which the connection means prevent the elongate member from sliding relative to the body.
Thus, the unlocked state enables adjustment of position to be performed simply, precisely, and quickly, while the locked state enables the selected position to be locked quickly. As a result, such a system can be operated simply, precisely, and quickly.
Advantageously, the connection means are arranged to prevent the elongate member from sliding relative to the body by a wedging effect.
Advantageously, the connection means comprise at least m one elastically deformable element.
Advantageously, the deformable element is suitable for implementing a wedging effect.
Advantageously, the system is arranged in such a manner that in the locked state, sliding is locked in a single direction.
Advantageously, the deformable element presents a bearing surface, and the elongate member presents a contact face suitable for coming into contact with the bearing surface in the locked state.
Thus, the longitudinal member entrains the deformable element towards the locked position because of the contact between the contact face and the bearing surface and without any intervention by the operator on the deformable element. The operator does not act on the deformable element, so the operator""s hands do not come into contact with sharp edges. As a result there is no risk of damaging or tearing gloves during the operation.
Advantageously, the contact face is smooth, locking being obtained by friction.
Advantageously, the contact face is knurled.
Advantageously, the bearing surface includes knurling.
Advantageously, the contact face presents recesses, in particular grooves.
Advantageously, the bearing surface has a projection suitable for being received in the recesses.
Advantageously, the deformable element is split over all or part of its length.
Advantageously, the deformable element has deformable tongues at one end.
Advantageously, the deformable element has an end for implementing unlocking.
Advantageously, the deformable element is conical in shape.
Advantageously, the end for implementing unlocking includes a bearing rim.
Advantageously, the connection means include a second elastically deformable element.
Advantageously, the second deformable element is suitable for preventing sliding in the other direction of displacement.
Advantageously, the second deformable element is a mirror image of the first deformable element.
Advantageously, the body can be dismantled into at least two portions.
Advantageously, the body includes connection means for interconnecting the two portions, in particular, a ring.